The invention is directed to improvements in temperature sensors having a carrier body, a temperature-dependent resistor element, and a protective sheath about said resistor element. A temperature sensor is already known in which the temperature-dependent electrical resistor element is completely surrounded by a protective sheath in order to protect it from adverse mechanical and chemical influences. As a result, when there are changes in temperature there is a relatively long delay period until the temperature-dependent electrical resistor element has detected the temperature change. When a temperature sensor of this kind is used to measure the air intake temperature of the internal combustion engine, such a delay in temperature detection means that the electrical fuel injection system controlled by this temperature sensor will be undesirably "late" in correcting for an excessively rich or excessively lean fuel-air mixture; in consequence, the proportion of toxic components in the exhaust gas is increased, and there may be an impairment in engine smoothness as well as an increase in the engine's tendency to knock or detonate.